When terrorists have been arrested sinister facts have emerged about how close they were to committing mass murder.

He said: “Most people detained in our country and considered linked to ISIS were very close to actually carrying out attacks and killing others.

“I say it openly: we will have to pay a price as well.

“The investigations, often subsequent to repatriations, have shown that most people arrested in our country with links to ISIS were very close to actually carrying out attacks and killing others.”

But Mr Gabrielli admitted his own police force needed to become better at actually firing their weapons at terrorists.

He said: “The first thing I focused on when I arrived was the shooting practice. But our police officers, at times, are a bit reluctant to ensure that training is constant.

“There are things to do about this issue, but there are also facts that prove how we are.”

However, the Italian law enforcer was complimentary about the close ties between European intelligence agencies, saying a good working relationship between EU nations helps make the world a safer place.

He said: “We are living a very lucky moment from this point of view. We have an excellent relationship with international police forces and we collaborate actively.”